The new 2e version has been significantly beefed up, as I understand it. It's now 3 books, a 280-page campaign book, a 215-page Trojan Reach sector book (including Aslan PC rules and background) and a 95-page Ships of the Reach book. Plus a big Trojan Reach map and some fancy deckplans for the Harrier.
The Drinax Companion adds another 220-pages of stuff, including all the previously published mini-expansion pdfs. There's more details on the worlds of the Torpol cluster and the Theev cluster, detailed rules for running the Harrier including upgrades, 6 or 7 of the adventure seeds from the Trojan Reach book expanded out into ~10 page adventures, more piracy rules including building pirate bases, ship encounters, more ships and extra equipment. Very recommended by me if you are going to run Pirates of Drinax.
Shadows of Sindal I don't have, but I understand it's another smaller campaign you can interweave with Pirates. And the Trojan Reach adventures can all be wiggled in to the campaign if you like.
I paid £20 for the Pirates PDFs, which was a good deal. I then bought half of the expansions for about £15 in a sale, then paid another £20 for the Drinax Companion with the rest, and I still think I got my money's worth out of the deal.
I'm working my group through Shadows of Sindal at the moment. Short version, there's someone else with a similar idea to King Oleb but different methods; over the course of three linked adventures, the PCs get entangled with the new guy's plots and either stop him, help him, or steal his ideas. It could be run standalone but IMHO it works best when woven into the main Pirates campaign.